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Heated humidified high-flow nasal cannula for preterm infants: An updated systematic review and meta-analysis
Nigel Fleemana, MPH, Yenal Dundara, MPhil, MRCPsych, Prakesh S Shahb, MBBS, MD, MSc, DCH, MRCP, FRCPC, Ben (NJ) Shawc, MRCP, FRCPCH, MD, MA (Clin
Ed)
Affiliations: aLiverpool Reviews and Implementation Group, Department of Health Services Research, University of Liverpool, Liverpool, UK; bDepartments of Paediatrics and Institute of Health Policy, Management and Evaluation, University of Toronto, Mount Sinai Hospital, Toronto, Canada; and cNeonatal Unit, Liverpool Women’s NHS Foundation Trust, Liverpool, UK.
Address correspondence to: Nigel Fleeman, Research Fellow, Liverpool Reviews and Implementation Group, University of Liverpool, Room, Whelan Building, The Quadrangle, Brownlow Hill, Liverpool, L69 3GB, [[email protected]], +44 (0)151 795 [email protected]
Short title: Systematic review of HHHFNC for preterm infants
Word count, abstract: 233
Word count, text minus with headings: 3862
Word count, text minus headings: 3784
1
ABSTRACT
Background: Heated humidified high flow nasal cannula (HHHFNC) is gaining popularity as
a mode of respiratory support. We updated a systematic review and meta-analyses
examining the efficacy and safety of HHHFNC compared with standard treatments for
preterm infants. The primary outcome was the need for reintubation for preterm infants
following mechanical ventilation (post-extubation analysis) or need for intubation for preterm
infants not previously intubated (analysis of primary respiratory support)
Methods: We searched PubMed, MEDLINE, Embase and the Cochrane Library for
randomised controlled trials (RCTs) of HHHFNC versus standard treatments. Meta-analysis
was conducted using Review Manager 5.3.
Results: The post-extubation analysis included ten RCTs (n = 1201) and the analysis of
primary respiratory support included ten RCTs (n = 1676). There were no statistically
significant differences for outcomes measuring efficacy, including the primary outcome.
There were statistically significant differences favouring HHHFNC versus nasal cannula
positive airway pressure (NCPAP) for air leak (Post-extubation, risk ratio [RR] 0.29, 95%
confidence interval [CI] 0.11 to 0.76, I2 = 0) and nasal trauma (Post-extubation: 0.35, 95% CI
0.27 to 0.46, I2 = 5%; Primary respiratory support: RR 0.52, 95% CI 0.37 to 0.74; I2 = 27%).
Studies, particularly those of primary respiratory support, included very few preterm infants
with gestational age (GA) <28 weeks.
Conclusions: HHHFNC may offer an efficacious and safe alternative to NCPAP for some
infants but evidence is lacking for preterm infants with GA ≤28 weeks.
KEY WORDS
Preterm, heated-humidified high-flow nasal cannula, systematic review, meta-analysis
2
Funding source: This project was originally funded by the National Institute for
Health Research Health Technology Assessment Programme (project number
14/151/03). See the Health Technology Assessment programme website for further
project information: http://www.nets.nih r .ac.uk/programmes/hta .
The views and opinions expressed herein are those of the authors and do not
necessarily reflect those of the National Institute for Health and Care Excellence or
the Department of Health
Financial disclosure: The authors have no financial relationships relevant to this
article to disclose.
Conflict of Interest: The authors have no conflicts of interest to disclose
Study registration: The original review is registered as PROSPERO
CRD42015015978. https://www.crd.york.ac.uk/PROSPERO/display_record.php?
RecordID=15978
Acknowledgements: Thank you to all our co-authors of the original review. Thank
you also to Dr Rabeea’h Aslam who assisted with the selection of studies for the
updated review and Miss Marty Richardson who provided statistical advice regarding
the updated meta-analyses.
3
BACKGROUND
While the majority of infants are born at term, data from Canada (1) and the UK (2) report
that approximately 6% to 7% of all infants are born preterm (i.e. before 37 completed weeks
of gestation). Respiratory problems are one of the most common causes of morbidity in
preterm infants (3). Many preterm infants therefore require respiratory support, which is
usually provided by mechanical endotracheal ventilation, nasal cannula positive airway
pressure (NCPAP), oxygen by incubator, headbox or low-flow nasal cannula (hereafter
referred to more simply as ‘oxygen’) and non-invasive positive pressure mechanical
endotracheal ventilation (NIPPV). All of these interventions have both long and short-term
risks, in particular nasal trauma, lung injury, infection and bronchopulmonary dysplasia
(BPD) (3-7).
Heated humidified high flow nasal cannula (HHHFNC) offers an alternative mode of
respiratory support and is gaining popularity (8). In 2016 we published a review of the
effectiveness of HHHFNC versus standard treatments on behalf of the National Institute for
Health Research Health Technology Assessment Programme (9). We found a lack of
evidence to suggest that HHHFNC is superior or inferior to standard treatments. We
concluded that more RCT evidence comparing HHHFNC with standard treatments was
required to inform the evidence base. Given that further RCTs have been published since
2016, in the current paper, we update the evidence for HHHFNC versus standard
treatments.
METHODS
Search strategyWe searched PubMed, MEDLINE, Embase, the Cochrane Library and trial and research
registers from 2000 to January 2015 (original review (9)) and PubMed, MEDLINE, Embase,
the Cochrane Library to March 2018 for the updated search. Search terms included a
combination of index terms (for the study population of preterm infants) and free-text words
4
(for the interventions involved). No study design or language filters were applied.
Bibliographies of previous reviews and retrieved articles were searched for further studies.
The search terms used for each database are presented in Supplementary Tables 1 to 4.
Study selectionRetrieved citations were assessed for inclusion in two stages. Two reviewers independently
scanned all titles and abstracts. Full-text copies of the selected studies were subsequently
obtained and assessed independently by two reviewers for inclusion (Supplementary Figure
1). Studies were included if they were RCTs of HHHFNC in preterm infants (i.e. before 37
completed weeks of gestation). Studies were excluded if they did not include preterm infants
(or a subgroup analysis of preterm infants) or did not include a comparison of HHHNFC with
a standard treatment (NCPAP, oxygen or NIPPV). Importantly, studies of interventions,
which did not clearly state that they used heated high flow were excluded. Disagreements
were resolved by discussion at each stage.
Data Extraction and assessment of risk of biasIndividual study data relating to study designs and findings were extracted by one reviewer
using a pre-tested data extraction form and independently checked for accuracy by a second
reviewer. When studies included preterm and non-preterm infants, only data for preterm
infants were extracted and study authors were contacted for missing data as necessary. The
risk of bias assessment was conducted by two reviewers independently using criteria
adapted from the Centre for Reviews and Dissemination (CRD) at the University of York
(10). Disagreements were resolved through consensus (10)
Data synthesisIn order to be consistent with our original review (9) we aimed to conduct two separate
analyses with a range of outcomes. First, we aimed to consider the evidence for preterm
5
infants treated following mechanical endotracheal ventilation (post-extubation). Second, we
aimed to consider the evidence for preterm infants not previously ventilated (primary
respiratory support). The primary outcome for both analyses was treatment failure. For post-
extubation, we defined this as the need for reintubation. For the analysis of primary
respiratory support, we defined this as the need for intubation. Secondary outcomes
included bronchopulmonary dysplasia (BPD), death, air leak and nasal trauma.
Where data permitted, a meta-analysis of primary and secondary outcomes was conducted
using Review Manager 5.3 software (The Cochrane Collaboration, London, UK). For these
outcomes, the risk ratio (RR) and the corresponding 95% Confidence Intervals (CI) were
reported. Heterogeneity was explored through consideration of the study populations (e.g.
differences in gestational age [GA]), interventions (e.g. starting flow rate for HHHFNC),
outcome definitions (e.g. different definitions for reintubation) and in statistical terms by the
Chi2 test for homogeneity and the I2 statistic (11). The I2 statistic with a level of >50% was
considered to indicate moderate levels of heterogeneity, and the Chi2 test, P <0.10 to
indicate statistically significant heterogeneity. Based on these assessments, a decision was
made on whether to combine the results using a fixed-effects model (in the case of minimal
heterogeneity) or a random-effects model (in the case of substantial levels of heterogeneity).
For each outcome, to summarise the findings in the context of the quality of the studies, we
applied the Grading of Recommendations Assessment, Development and Evaluation
(GRADE) criteria (12). These criteria enabled us to assess the size, precision and
consistency of findings alongside the risk of bias and indirectness across studies.
RESULTS
Included studiesTwenty-six records (13-38) reporting on 19 separate RCTs (13, 14, 16-19, 21-25, 27, 30, 31,
33, 35-38) were included in the systematic review (Supplementary Figure 1). Ten studies
6
(13, 14, 16, 17, 21, 22, 27, 30, 36, 37) met the criteria for post-extubation analysis and ten
studies (18, 19, 23-25, 31, 33, 35, 37, 38) met the criteria for the analysis of primary
respiratory support. We included one of the studies in both analyses as the study included
infants who had been treated following mechanical endotracheal ventilation and those who
had not been previously ventilated (37). For the update, we used data reported for this study
in a previous Cochrane review (39).
Study characteristics The characteristics of the studies included in the post-extubation analysis are summarised in
Table 1 and the characteristics of the studies included in the analysis of primary respiratory
support are summarised in Table 2. The flow rates for HHHFNC varied across studies
included in both the post-extubation analysis and analysis of primary respiratory support.
Generally, flow rates were lower in the earlier published studies. As expected, birth weight
was generally lower in those studies relevant to the post-extubation analysis than those in
the analysis of primary respiratory support.
Characteristics of studies included in the post-extubation analysisA total of 1201 preterm infants were included in the ten studies (13, 14, 16, 17, 21, 22, 27,
30, 36, 37) relevant to the post-extubation analysis. All studies compared HHHFNC with
NCPAP. Two of the studies included both preterm infants and infants born at or after term
(14, 37) where we only reported data relating to preterm infants. The size of the populations
of preterm infants included in the studies ranged from 49 (36) to 303 (27). Where reported,
the GA of study participants varied across studies. In four studies the mean or median GA
was approximately 27 to 28 weeks (16, 17, 27, 36), 29 weeks in one study (22) and
approximately 32 weeks in three other studies (13, 21, 30). Participants in nine studies
included in the post-extubation analysis received surfactant prior to trial entry (13, 14, 16, 17,
21, 27, 30, 36, 37) whereas it is unclear in one study (22).
7
Characteristics of studies included in the analysis of primary respiratory supportThe ten studies relevant to the analysis of primary respiratory support (18, 19, 23-25, 31, 33,
35, 37, 38) included a crossover trial in which preterm infants were only treated for 24 hours
before crossing over to the other treatment arm (23). Nine studies compared HHHFNC with
NCPAP (18, 19, 23, 25, 31, 33, 35, 37, 38) and one pilot study compared HHHFNC with
NIPPV (24).
A total of 1600 preterm infants were involved in the studies of HHHFNC versus NCPAP and
the study sizes ranged from 20 (23) to 564 (33). The trial comparing HHHFNC with NIPPV
included 76 infants (24). In most studies, where reported, the mean GA at baseline was
approximately 32 to 33 weeks (18, 19, 24, 25, 31, 35, 38). In the crossover trial by
Klingenberg et al 2014 (23) the mean GA was 29 weeks and in Glackin et al 2016 (18) the
mean GA was 27 weeks.
Only the study by Yoder et al (37) which also included preterm infants (included in the post-
extubation analysis), included participants who had received previous treatment with
surfactant. Two studies explicitly excluded preterm infants who had previously received
surfactant (33, 35). Surfactant was permitted for preterm infants who met pre-specified
criteria as part of their treatment in three other studies (19, 25, 38). It is unclear if participants
received prior or concurrent surfactant in four studies (18, 23, 24, 31).
Assessment of risk of biasThe findings from the risk of bias assessment are presented in Supplementary Tables 5 and
6. There were concerns regarding the risk of bias in one study by Kadivar et al (21) included
in the post-extubation analysis. It was unclear from this study how many preterm infants
8
were enrolled or included in the analysis as the CONSORT flow diagram indicates that there
were 108 patients randomised in the trial, of whom 90 were included in the analysis.
However, it is reported elsewhere in the paper that only 54 patients were enrolled (which is
also reported to be the required sample size). Analyses were reported for 54 patients (27
participants in each arm). We therefore consider this study to be at high risk of reporting
bias.
Findings
Efficacy findings from post-extubation analysisThere were no statistically significant differences between HHHFNC and NCPAP in terms of
efficacy (Table 3, Supplementary Figure 2). There were few deaths in either arm: nine
(1.7%) of 508 preterm infants treated with HHHFNC and 13 (2.5%) of 512 preterm infants
treated NCPAP.
Since the study by Kadivar et al (21) was considered to be at high risk of reporting bias and
only included a maximum flow rate for participants randomised to HHHFNC of 4 L/min, this
was excluded from a sensitivity analysis of reintubation within 3 days. This had minimal
impact on the results (RR 0.92, 95% CI 0.57 to 1.51; I2 = 0%).
Safety findings from post-extubation analysis As evident from Table 3 and Supplementary Figure 3, HHHFNC reduced the incidence of air
leak and nasal trauma versus NCPAP (RR 0.29, 95% CI 0.11 to 0.79; I2 = 0% and RR 0.35,
95% CI 0.27 to 0.46; I2 = 5%, respectively). However, air leak rarely occurred in either arm:
three (0.6%) of 518 preterm infants treated with HHHFNC and 15 (2.9%) of 519 preterm
infants treated with NCPAP.
9
Efficacy findings from analysis of primary respiratory support There were no statistically significant differences between HHHFNC and NCPAP in terms of
efficacy (Table 4, Supplementary Figure 4). As with the post-extubation analysis, there were
few deaths in either arm: five (0.7%) of 717 preterm infants treated with HHHFNC and five
(0.7%) of 741 preterm infants treated NCPAP. There were no statistically significant
differences in efficacy outcomes for HHHFNC versus NIPPV (Supplementary Table 7).
Safety findings from analysis of primary respiratory support Safety findings are reported in Table 4 and Supplementary Figure 5. HHHFNC reduced the
incidence of nasal trauma versus NCPAP (RR 0.52, 95% CI 0.37 to 0.74; I2 = 27%) but there
were no statistically significant differences between arms in the incidence of air leak. As with
the post-extubation analysis, there were few occurrences of air leak in either arm: 15 (2.1%)
of 702 preterm infants treated with HHHFNC and 18 (2.8%) of 727 preterm infants treated
with NCPAP. There were no statistically significant differences for either air leak or nasal
trauma for HHHFNC versus NIPPV (Supplementary Table 7).
GRADE rating of evidenceUsing the GRADE criteria, for the majority of outcomes comparing HHHFNC with NCPAP,
the quality of evidence for each outcome (for HHHFNC versus NCPAP) is considered to be
moderate (Table 3 and Table 4). For the comparison of HHHFNC versus NIPPV, because
evidence is derived from only one relatively small pilot study, the quality of evidence is
considered to be very low (Supplementary Table 7).
DISCUSSIONOur updated literature search identified an additional 12 studies (13, 17-19, 21, 22, 25, 30,
33, 35, 36, 38) to those included in our previous review published in 2016 (9) and an
additional ten studies (13, 17, 18, 21-23, 25, 33, 35, 36) to those included in the other most
10
recently published systematic review, a Cochrane review published in 2016 by Wilkinson et
al (39). Our update has not found any consistent and statistically significant differences
between HHHFNC and NCPAP (or NIPPV) for the majority of efficacy outcomes, including
the primary outcome of treatment failure; similar findings have been reported from previous
meta-analyses (9, 39, 40). However, we found that meta-analysis of adverse event rates
from studies indicates statistically significantly fewer adverse events with HHHFNC than with
NCPAP as measured by air leak (for the post-extubation analysis) and nasal trauma (for
both the post-extubation analysis and analysis of primary respiratory support). The reduced
incidence in nasal trauma identified by our review is one of the expected benefits of
HHHFNC, as previously reported by the authors of two meta-analyses (39, 40). A statistically
significant reduction in air leak has not however been previously demonstrated by meta-
analysis. This reduction in air leak using HHHFNC for post-extubation compared to using
NCPAP is an important finding. Air leak may cause hypoxia and increase the risk of
intraventricular haemorrhage.
Given the apparent lack of difference in efficacy outcomes (treatment failure, BPD, death)
between HHHFNC and NCPAP, the decision to use HHHFNC post-extubation will be a
clinical one depending on the individual baby, perhaps taking into account their GA and size.
The numbers of preterm infants needed to treat (NNT) with HHHFNC versus NCPAP in
order to prevent occurrences of nasal trauma or air leak may also be a consideration. The
NNT can only be meaningfully interpreted where there is a statistically significant difference
between treatments (41). From the results presented in our review, as a post-extubation
treatment, four (95% CI 4 to 5) preterm infants should receive HHHFNC versus NCPAP in
order to prevent nasal trauma. The NNT for air leak is much larger and associated with
greater uncertainty: 49 (95% CI 39 to 144) preterm infants should receive HHHFNC versus
NCPAP in order to prevent air leak. As a treatment for primary respiratory support, 15 (95%
CI 11 to 27) preterm infants should receive HHHFNC versus NCPAP in order to prevent
nasal trauma.
11
While we found no evidence of statistically significant differences between HHHFNC and
NCPAP (or NIPPV) for the efficacy outcomes, this does not necessarily mean that the two
interventions are equivalent or that HHHFNC is noninferior to NCPAP (or NIPPV). Indeed, in
our previous review (9) we highlighted the need for large noninferiority trials to be conducted.
Our original review did include one reasonably large (n = 303) noninferiority trial comparing
HHHFNC with NCPAP for post-extubation conducted by Manley et al (28). This reported
HHHFNC to be noninferior to NCPAP, utilising a composite outcome for treatment failure
(28). Our updated review includes three additional noninferiority trials, all of primary
respiratory support, from the large HIPSTER trial (n = 564) (33) and RCTs conducted by
Lavizzari et al (n = 316) (25) and Murki et al (n = 279) (38). The results from the study by
Lavizzari et al (25) found HHHFNC to be noninferior to NCPAP for the primary outcome
(need for intubation within 3 days (25)). However, the HIPSTER trial and the trial by Murki et
al not only failed to show HHHFNC to be noninferior but found the difference between arms
to be statistically significant in favour of NCPAP, again utilising a composite outcome for
treatment failure (33, 38). As a result of the large difference between interventions in
treatment failure in both these studies, the trials were stopped early. It should however be
noted that intubation rates were relatively similar between arms in both studies.
Aside from the previously cited systematic reviews, we are aware of a recently published
rapid review of HHHFNC (42). This review was more limited than ours both in scope (as it
focussed on HHHFNC as a treatment for primary respiratory support) and eligibility (the
review was limited to studies in English). Searches were also conducted in June 2017,
whereas ours were last conducted in March 2018. It therefore included fewer studies. As
with our review, it found no statistically significant differences between HHHFNC and
NCPAP in the need for intubation or BPD. It did however find that HHHFNC used for primary
respiratory support resulted in a higher rate of treatment failure than NCPAP, using the
study-defined outcomes of treatment failure in each study.
12
For our review, we have used a simple of definition of treatment failure for both the post-
extubation analysis (need for reintubation) and analysis of primary respiratory support (need
for intubation). For the post-extubation analysis, four studies used a composite outcome for
treatment failure (15, 17, 27, 36). Six studies used a composite outcome for treatment failure
in the analysis of primary respiratory support (19, 24, 31, 33, 35, 38). Five of these studies
(19, 24, 31, 33, 35) were included in the recent rapid review (42). Only the study of HHHFNC
for primary respiratory support by Lavizzari et al (25) (also included in the rapid review) used
a similar definition of treatment failure (the need for intubation). Unlike the authors of the
rapid review (42) and Cochrane review (39), we did not pool data into a meta-analysis for
study-defined treatment failure because the definitions varied across studies. We note,
however, that aside from these trials (33, 38) there were no statistically significant
differences reported for treatment failure between HHHFNC and NCPAP reported in any
other individual trial (15, 17, 19, 24, 27, 31, 35, 36).
Another important consideration, however, is that in many instances where treatment failure
was defined, it was reported that ‘rescue’ treatment was permitted prior to the need for
reintubation or intubation. For post-extubation treatment, this constituted NCPAP (27, 38)
NCPAP with additional ventilation delivered breaths (15) NIPPV (17) and bilevel CPAP or
NIPPV (36). ‘Rescue’ treatment rates varied from 3% (15) to 75% (36) for infants treated
with HHHFNC compared with 7% (15) to 65% (36) for infants treated with NCPAP. For
primary respiratory support, where reported, ‘rescue’ treatment constituted surfactant for
participants treated with HHHFNC or NIPPV (24), NCPAP for participants treated with
HHHFNC (33) and bilevel CPAP for participants treated with HHHFNC or NCPAP (35).
‘Rescue’ treatment rates varied from 19% (35) to 39% (33) for infants treated with HHHFNC
and were 11% for infants treated with NCPAP (35) and 34% for infants treated with NIPPV
(24). Given the use of ‘rescue’ treatment in some of the trials, the authors of a recent
13
narrative review state that ‘rescue’ treatment is an important part of the treatment pathway in
both post-extubation treatment and primary respiratory support (43).
The main strength of our review is that it includes the most up-to-date published evidence
from 19 studies (13, 14, 16-19, 21-25, 27, 30, 31, 33, 35-38). We have also applied the
GRADE criteria to each outcome. There are however two potential limitations. First, while
there was little statistical heterogeneity detected in the analyses we conducted, there were
however minor notable differences in baseline characteristics across studies in terms of GA
of included participants and HHHFNC flow rates. Nonetheless, using the GRADE criteria, we
considered there to be no serious issues with the quality of the evidence in relation to
consistency. Second, while studies included in the post-extubation analysis included
participants who had received surfactant prior to trial entry (13, 14, 16, 17, 21, 22, 27, 30,
36, 37) two studies included in the analysis of primary respiratory support explicitly excluded
preterm infants who had previously received surfactant (33, 35). It is unclear to what extent,
if any, these differences impact on the outcomes. However, the low number of participants
with GA <28 weeks in the studies included, particularly in the analysis of primary respiratory
support, raises questions about the suitability of using HHHFNC for this subgroup of preterm
infants. Three studies of post-extubation treatment have examined efficacy in preterm infants
with very low GA, <26 weeks (27) or ≤28 weeks (15, 36). Findings appear to favour NCPAP
in relation to composite outcomes of treatment failure (27, 36) and HHHFNC in terms of the
need for reintubation (15). However, findings were not reported as being statistically
significantly different in these studies. For primary respiratory support, similar subgroups
have not been defined (these studies typically including participants of greater GA than in
studies of post-extubation treatment). Hence it has been recommended by the authors of
recent reviews that HHHFNC is most suited for more mature infants (42, 43).
There are also methodological issues that warrant some discussion. First, for the outcomes
of death and air leak, there were relatively few events. It has been recommended that for
14
rare events, analyses are conducted using the Peto one-step odds ratio method (44). We
made no provision for analysing rare events in our protocol, but we did conduct post-hoc
analyses using the Peto method for these two outcomes. The odds ratios (ORs) derived
from the analyses using the Peto method were very similar to those of the RRs we found
from our original analyses. A second methodological issue to note is that including crossover
trials in meta-analyses can be problematic. In the crossover trial included in our review, the
outcomes were reported at two 24-hour intervals and were not relevant to this review. A third
methodological issue was that in two studies (14, 37), we only included relevant subgroup
populations of the overall trial populations in our meta-analyses. Neither trial was designed
in such a way that it was stratified for these subgroups and therefore randomisation was
broken. Thus, we conducted post-hoc sensitivity analyses excluding these two studies to
determine if their exclusion altered the results. Sensitivity analyses yielded very similar
results to those we found from our original analyses.
Finally, aside from the consideration of the clinical effectiveness of HHHFNC versus
standard treatment, other key factors to take into account when considering which
intervention to use for preterm interventions include evidence regarding the quality of care
and cost effectiveness of treatment. Findings from surveys of practitioners have found
HHHFNC enables family members to be more involved in the care of their infants (45) and to
be better tolerated by infants (46) than other treatment options. Evidence from a small
crossover trial (n = 20) also found parents preferred HHHFNC to NCPAP for these reasons
(23). Survey findings (45) and findings from a small RCT (n = 70) (19) also found HHHFNC
to be easier to use compared to other modalities, allowing health care, practitioners to more
easily handle and care for infants (45). Our previous review found that while the capital cost
of HHHFNC was lower than of NCPAP, consumable costs were higher (9). Therefore, at
machine lifespans over five years, as the difference between interventions in consumable
costs decrease, utilisation rates would also have to decrease in order for HHHFNC to remain
cost saving. The HIPSTER trial has since reported the difference in total treatment costs for
15
an inpatient admission for primary respiratory support (33). The study authors found the cost
difference of the treatment specific consumable equipment between the two interventions to
be neither statistically nor economically significant, with HHHFNC being US$17 cheaper on
average.
CONCLUSIONSSince our last review, a large number of RCTs have been published comparing HHHFNC to
NCPAP. There appears to be at least moderate quality evidence indicating that, compared
with NCPAP, the incidence of air leak and nasal trauma is reduced using HHHFNC for post-
extubation as is the incidence of nasal trauma for HHHFNC used as primary respiratory
support. However, there remains a lack of convincing clinical effectiveness evidence to
suggest a difference between HHHFNC and NCPAP for most of the other outcomes,
including all efficacy outcomes for post-extubation, and efficacy outcomes and air-leak for
primary respiratory support. Evidence for an effect between HHHFNC and NIPPV is
seriously lacking. There is therefore still the need for further research examining these
efficacy outcomes and also for investigating outcomes of HHHFNC versus NIPPV. We would
also recommend that further consideration should be given to future research including the
quality of care and costs of treatment. Further research is also needed into the efficacy and
safety of HHHFNC for infants with GA ≤28 weeks.
16
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positive airway pressure postextubation in premature infants. J Pediatr. 2013;162(5):949-54.e1.17. Elkhwad M, Dako J, Jennifer G, Harriet F, Anand K. Randomized control trial: heated humidity high flow nasal cannula in comparison with ncpap in the management of rds in extreme low birth infants in immediate post extubation period. J Neonat Pediatr Med. 2017;3(1).18. Glackin SJ, O'Sullivan A, George S, Semberova J, Miletin J. High flow nasal cannula versus NCPAP, duration to full oral feeds in preterm infants: a randomised controlled trial. Arch Dis Child Fetal Neonatal Ed. 2016;23:23.19. Iranpour R, Sadeghnia A, Hesaraki M. High-flow nasal cannula versus nasal continuous positive airway pressure in the management of respiratory distress syndrome. J Isfahan Med Sch. 2011;29(143):761-72.20. Iranpour R, Sadeghnia A, Hesaraki M. 393 High-flow nasal cannula versus nasal continuous positive airway pressure in the management of respiratory distress syndrome. Arch Dis Child. 2012;97(Suppl 2):A115-A6.21. Kadivar MM, Mosayebi ZM, Razi NM, Nariman SM, Sangsari RM. High flow nasal cannulae versus nasal continuous positive airway pressure in neonates with respiratory distress syndrome managed with insure method: a randomized clinical trial. Iran J Med Sci. 2016;41(6):494-500.22. Kang WQ, Xu BL, Liu DP, Zhang YD, Guo J, Li ZH, et al. [Efficacy of heated humidified high-flow nasal cannula in preterm infants aged less than 32 weeks after ventilator weaning]. Zhongguo Dang Dai Er Ke Za Zhi. 2016;18(6):488-91.23. Klingenberg C, Pettersen M, Hansen EA, Gustavsen LJ, Dahl IA, Leknessund A, et al. Patient comfort during treatment with heated humidified high flow nasal cannulae versus nasal continuous positive airway pressure: A randomised cross-over trial. Arch Dis Child Fetal Neonatal Ed. 2014;99(2):F134-f7.24. Kugelman A, Riskin A, Said W, Shoris I, Mor F, Bader D. A randomized pilot study comparing heated humidified high-flow nasal cannulae with NIPPV for RDS. Pediatr Pulmonol. 2014;50(6):576-83.25. Lavizzari A, Colnaghi M, Ciuffini F, Veneroni C, Musumeci S, Cortinovis I, et al. Heated, humidified high-flow nasal cannula vs nasal continuous positive airway pressure for respiratory distress syndrome of prematurity: a randomized clinical noninferiority trial. Jama, Pediatr. 2016;08:08.26. Ma L, Liu CQ, Gu XH, Liu XJ. The efficacy and safety of heated humidified high-flow nasal cannula for prevention of extubation failure in neonates. J Matern Fetal Neonatal Med. 2014;27:208-9.27. Manley BJ, Owen LS, Doyle LW, Andersen CC, Cartwright DW, Pritchard MA, et al. High-flow nasal cannulae vs. nasal cpap for post-extubation respiratory support of very preterm infants: A multicentre, randomised non-inferiority trial. J Paediatr Child Health. 2013;49:41.28. Manley BJ, Owen LS, Doyle LW, Andersen CC, Cartwright DW, Pritchard MA, et al. High-flow nasal cannulae in very preterm infants after extubation. N Engl J Med. 2013;369(15):1425-33.29. Mohammed E, Anand K, Joleen D, Jennifer G. Randomized control trial: heated humidity high flow nasal cannula in comparison with ncpap in the management of rds in extreme low birth infants in immediate post extubation period. J Neonat Pediatr Med. 2014;3:121.30. Mostafa-Gharehbaghi M, Mojabi H. Comparing the effectiveness of nasal continuous positive airway pressure (NCPAP) and high flow nasal cannula (HFNC)
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in prevention of post extubation assisted ventilation. Zahedan J Res Med Sci. 2014;17(6):e984.31. Nair G, Karna P. Comparison of the effects of vapotherm and nasal CPAP in respiratory distress in preterm infants. PAS. 2005;57:2054.32. Roberts CT, Owen LS, Manley BJ, Donath SM, Davis PG. A multicentre, randomised controlled, non-inferiority trial, comparing high flow therapy with nasal continuous positive airway pressure as primary support for preterm infants with respiratory distress (the HIPSTER trial): study protocol. BMJ Open. 2015;5(6):e008483.33. Roberts CT, Owen LS, Manley BJ, Froisland DH, Donath SM, Dalziel KM, et al. Nasal high-flow therapy for primary respiratory support in preterm infants. N Engl J Med. 2016;375(12):1142-51.34. Roberts CT, Owen LS, Manley BJ, Froisland DH, Donath SM, Pritchard MA, et al. High-flow nasal cannulae as primary respiratory support for preterm infants-an international, multi-centre, randomised, controlled, non-inferiority trial. J Paediatr Child Health. 2016;52:120.35. Shin J, Park K, Lee EH, Choi BM. Humidified high flow nasal cannula versus nasal continuous positive airway pressure as an initial respiratory support in preterm infants with respiratory distress: a randomized, controlled non-inferiority trial. J Korean Med Sci. 2017;32(4):650-5.36. Soonsawad S, Tongsawang N, Nuntnarumit P. Heated humidified high-flow nasal cannula for weaning from continuous positive airway pressure in preterm infants: a randomized controlled trial. Neonatology. 2016;110(3):204-9.37. Yoder BA, Stoddard RA, Li M, King J, Dirnberger DR, Abbasi S. Heated, humidified high-flow nasal cannula versus nasal CPAP for respiratory support in neonates. Pediatrics. 2013;131(5):e1482-90.38. Murki S, Singh J, Khant C, Kumar Dash S, Oleti TP, Joy P, et al. High-Flow Nasal Cannula versus Nasal Continuous Positive Airway Pressure for Primary Respiratory Support in Preterm Infants with Respiratory Distress: A Randomized Controlled Trial. Neonatology. 2018:235-41.39. Wilkinson D, Andersen C, O'Donnell CP, De Paoli AG, Manley BJ. High flow nasal cannula for respiratory support in preterm infants. Cochrane Database Syst Rev. 2016;2:CD006405.40. Kotecha SJ, Adappa R, Gupta N, John Watkins W, Kotecha S, Chakraborty M. Safety and efficacy of high-flow nasal cannula therapy in preterm infants: A meta-analysis. Pediatrics. 2015;136(3):542-53.41. Muthu V. The number needed to treat: problems describing non-significant results. Evid Based Ment Health. 2003;6(3):72.42. Conte F, Orfeo L, Gizzi C, Massenzi L, Fasola S. Rapid systematic review shows that using a high-flow nasal cannula is inferior to nasal continuous positive airway pressure as first-line support in preterm neonates. Acta Paediatr. 2018.43. Roberts CT, Hodgson KA. Nasal high flow treatment in preterm infants. Matern Health Neonatol Perinatol. 2017;3:15.44. Higgins JP, Green S, editors. Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0 [updated March 2011]: The Cochrane Collaboration. Available from http://handbook-5-1.cochrane.org/ (accessed January 23, 2019); 2011.45. Hough JL, Shearman AD, Jardine LA, Davies MW. Humidified high flow nasal cannulae: current practice in Australasian nurseries, a survey. J Paediatr Child Health. 2012;48(2):106-13.
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46. Ojha S, Gridley E, Dorling J. Use of heated humidified high-flow nasal cannula oxygen in neonates: a UK wide survey. Acta Paediatr. 2013;102(3):249-53.
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TABLES
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Table 1 Study and infant characteristics (Post-extubation analysis)Study Study design,
LocationHHHFNC flow rate
Arm (number of preterm infants)
Eligibility criteria
GA, mean (SD), weeks
Birth weight, mean (SD), g
Collins et al 2013(16) Single centre: Australia 8 L/min HHHNFC (n = 67)NCPAP (n = 65)
GA <32 weeks 27.9 (1.95)27.6 (1.97)
1123 (317)1105 (374)
Manley et al 2013(27) Multicentre, non-inferiority: Australia
5 L/min to 6 L/min
HHHNFC (n = 152)NCPAP (n = 151)
GA <32 weeks 27.7 (2.1)27.5 (1.9)
1041 (338)1044 (327)
Yoder et al 2013(37) Multicentre: United States
3 L/min to 8 L/min
HHHNFC (n = 75)NCPAP (n = 73)
No limitation on GA §
NR §NR §
NR §NR §
Collaborative group 2014(14)
Multicentre: China 3 L/min to 8 L/min
HHHNFC (n = 79)NCPAP (n = 71)
No limitation on GA §
NR §NR §
NR §NR §
Mostafa-Gharehbaghi 2014(30)
Single centre: Iran 6 L/min HHHNFC (n = 42)NCPAP (n = 43)
GA 30 to 34 weeks
32.24 (1.7)32.07 (1.48)
1905 (464)1885 (417)
Chen et al 2015(13) China 2 L/min to 8 L/min
HHHNFC (n = 34)NCPAP (n = 32)
GA <37 weeks 32 (5)32 (4)
NRNR
Kadivar et al 2016(21) Single centre: Iran ≤4 L/min HHHNFC (n = 27)*NCPAP (n = 27)*
GA 28 to 34 weeks
31.5231.33
16421601
Kang et al 2016(22) Single centre: China 5 L/min to 6 L/min
HHHNFC (n = 79)NCPAP (n = 82)
GA 26 to 31 weeks
29.1 (1.0)29.2 (1.1)
1400 (200) †1400 (200) †
Elkhwad et al 2017(17) Single centre: Qatar ≤5 L/min HHHNFC (n = 29)NCPAP (n = 24)
GA 24 to 28 weeks
26.8 (0.095)26.7 (0.95)
995 (202.82)995 (201.66)
Sonsawad et al 2017(36) Single centre: Thailand 4 L/min to 6 L/min
HHHNFC (n = 24)NCPAP (n = 25)
GA <32 weeks 27.5 (26, 30) #28 (25, 29.5) #
990 (800, 1333) #980 (740, 1237) #
GA = gestational age; NR = not reported; SD = standard deviation § Study included both preterm infants and infants born at or after term (data not reported for preterm infants only)* The PRISMA flow diagram for this study indicates 108 participants were in fact randomised, 54 in each arm† Data reported as Kg in published paper; # Median (interquartile range)
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Table 2 Study and infant characteristics (Analysis of primary respiratory support)Study Study design, Location HHHFNC
flow rateArm (number of preterm infants)
Eligibility criteria
GA, mean (SD), weeks
Birth weight, mean (SD) g
Nair and Karna 2005(31)
Single Centre: United States 1.8 L/min HHHNFC (n = 13) †NCPAP (n = 15) †
GA 27 to 34 weeks
32 (0.5)31 (0.5)
1675 (139)1493 (64)
Iranpour et al 2011(19)
Single centre: Iran 1.5 L/min to 3 L/min
HHHFNC (n = 35)NCPAP (n = 35)
GA 30 to 35 weeks
32.3 (1.6)33.0 (1.9)
1824 (410)2021 (498)
Yoder et al 2013(37) Multicentre: United States 3 L/min to 8 L/min
HHHNFC (n = 58)NCPAP (n = 67)
No limitation on GA §
NR §NR §
NR §NR §
Klingenberg et al 2014(23)
Single centre, cross over: Norway
5 L/min to 6 L/min
HHHNFC / NCPAP (n = 20) *
GA <34 weeks 29.3 (1.7) * 1234 (353) *
Kugelman et al 2014(24)
Single centre: Israel 1 L/min to 5 L/min
HHHFNC (n = 38)NIPPV (n = 38)
GA <35 weeks 31.8 (2.3)32.0 (2.3)
1759 (488)1835 (530)
Glackin et al 2016(18)
Single centre: Ireland 7 L/min HHHNFC (n = 22)NCPAP (n = 22)
GA <30 weeks 26.9 (1.5)27.3 (1.5)
868 (160)891 (202)
Lavizzari et al 2016(25)
Single centre non-inferiority: Italy
4 L/min to 6 L/min
HHHNFC (n = 158)NCPAP (n = 158)
GA (29 weeks to 36 weeks
33.1 (1.9)33.0 (2.1)
1968 (581)1908 (528)
Roberts et al 2016(33)
Multi-centre non-inferiority: Australia and Norway
6 L/min to 8 L/min
HHHNFC (n = 278)NCPAP (n = 286)
GA ≥28 weeks 32.0 (2.1)32.0 (2.2)
1737 (580)1751 (599)
Shin et al 2017(35) Single centre non-inferiority: South Korea
3 L/min to 7 L/min
HHHNFC (n = 42)NCPAP (n = 43)
GA >30 to <35 weeks
32.5 (1.5)33.0 (1.2)
2058 (371)1996 (374)
Murki et al 2018(38) Two centre non-inferiority: India
5 L/min to 7 L/min
HHHNFC (n = 133)NCPAP (n = 139)
≥28 weeks 31.8 (1.9)31.6 (2.2)
1632 (431)1642 (437)
GA = gestational age; NR = not reported; SD = standard deviation § Study included both preterm infants and infants born at or after term (data not reported for preterm infants only)* Klingenberg et al 2014(23) was a cross-over study in which 20 preterm infants were randomised to 24 hours of treatment with NCPAP or HHHFNC followed by 24 hours of the alternate therapy; relevant data by arm (including the number initially randomised to each arm) not reported† Data reported here are taken from the abstract
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Table 3 GRADE ratings for each outcome for HHHFNC versus NCPAP (Post-extubation analysis: preterm infants treated following mechanical endotracheal ventilation)
Certainty assessment a № of patients Effect Overall certainty
of evidence (Quality)
Outcome / importance
№ of studies Risk of bias Inconsistency Indirectness Imprecision HHHFNC NCPAP Relative
(95% CI)Absolute(95% CI)
Reintubation <3 days/ Critical
5 not serious b not serious not serious serious c 40/234 (17.1%)
33/244 (13.5%)
RR 1.24(0.81 to
1.89)
32 more per 1,000(from 26 fewer to
120 more)
⨁⨁⨁◯Moderate
Reintubation <7 days/ Important
5 not serious not serious not serious serious c 66/411 (16.1%)
83/421 (19.7%)
RR 0.84(0.63 to
1.12)
32 fewer per 1,000(from 24
more to 73 fewer)
⨁⨁⨁◯Moderate
BPD/ Important
8 not serious not serious not serious serious c 113/560 (20.2%)
133/570 (23.3%)
RR 0.86(0.70 to
1.06)
33 fewer per 1,000(from 14
more to 70 fewer)
⨁⨁⨁◯Moderate
Death/ Critical 7 not serious not serious not serious serious c 9/508 (1.8%)
13/512 (2.5%)
RR 0.71(0.31 to
1.60)
7 fewer per 1,000(from 15
more to 18 fewer)
⨁⨁⨁◯Moderate
Air leak/ Important
7 not serious not serious not serious serious c 3/518 (0.6%)
15/519 (2.9%)
RR 0.29(0.11 to
0.76)
21 fewer per 1,000
(from 7 fewer to
26 fewer)
⨁⨁⨁◯Moderate
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Certainty assessment a № of patients Effect Overall certainty
of evidence
Outcome / importance
№ of studies Risk of bias Inconsistency Indirectness Imprecision HHHFNC NCPAP Relative
(95% CI)Absolute(95% CI)
Nasal trauma/ Important
7 not serious not serious not serious serious c 54/428 (12.6%)
154/432 (35.6%)
RR 0.35(0.27 to
0.46)
232 fewer per 1,000(from 193 fewer to
260 fewer)
⨁⨁⨁◯Moderate
BPD = bronchopulmonary dysplasia; HHHFNC = heated humidified high-flow nasal cannula; NCPAP = nasal continuous positive airways pressure
a. The GRADE criteria for the certainty assessment also include an assessment of publication bias. It was not possible to test for publication bias by use of funnel plots as we did not include 10 or more studies in any analysis, however, we do not consider there are any reasons to suspect there is any evidence of publication bias
b. While there was high risk of reporting bias in one study which reported this outcome (21), we found that excluding this study from analysis made little difference to the pooled relative effect. Therefore, we did not downgrade the quality of the evidence
c. For most outcomes, there are relatively few events and consequently wide confidence intervals, therefore we downgraded the quality of the evidence. Although for nasal trauma, confidence intervals are reasonably narrow, we considered it conservative to downgrade the quality of the evidence for this outcome as a result of the relatively few events identified across the studies
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Table 4 GRADE ratings for HHHFNC versus NCPAP (Analysis of primary respiratory support: Preterm infants with no prior mechanical endotracheal ventilation)
Certainty assessment a № of patients Effect Overall certainty of
evidence (Quality)
Outcome № of studies Risk of bias Inconsistency Indirectness Imprecision HHHFNC NCPAP Relative
(95% CI)Absolute(95% CI)
Intubation/ Critical
6 not serious not serious not serious serious b 90/704 (12.8%)
81/728 (11.1%)
RR 1.15(0.87 to 1.52)
17 more per 1,000(from 14 fewer to 58 more)
⨁⨁⨁◯Moderate
BPD/ Important
6 not serious not serious not serious serious b 27/348 (7.8%)
24/359 (6.7%)
RR 1.14(0.75 to 1.75)
9 more per 1,000(from 17 fewer to 50 more)
⨁⨁⨁◯Moderate
Death/ Critical
7 not serious not serious not serious serious b 5/717 (0.7%)
5/741 (0.7%)
RR 1.03(0.32 to 3.33)
0 fewer per 1,000
(from 5 fewer to 16 more)
⨁⨁⨁◯Moderate
Air leak/ Important
6 not serious not serious not serious serious b 15/702 (2.1%)
18/727 (2.5%)
RR 0.88(0.46 to 1.67)
3 fewer per 1,000(from 13 fewer to 17 more)
⨁⨁⨁◯Moderate
Nasal trauma/ Important
6 not serious not serious not serious serious b 42/578 (7.3%)
85/601 (14.1%)
RR 0.52(0.37 to 0.74)
68 fewer per 1,000(from 37 fewer to
89 fewer)
⨁⨁⨁◯Moderate
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BPD = bronchopulmonary dysplasia; HHHFNC = heated humidified high-flow nasal cannula; NCPAP = nasal continuous positive airways pressure
a. The GRADE criteria for the certainty assessment also include an assessment of publication bias. It was not possible to test for publication bias by use of funnel plots as we did not include 10 or more studies in any analysis, however, we do not consider there are any reasons to suspect there is any evidence of publication bias
b. For all outcomes, there are relatively few events and consequently wide confidence intervals, therefore we downgraded the quality of the evidence
27